1. Field of the Invention
This invention relates to pressure relief means.
2. Prior Art
There are known valves for water pipes, essentially consisting of a housing with an inlet opening and an outlet opening, between these both openings there being arranged a through-flow chamber in which there is a spring biassed valve spindle provided with sealing means, arranged to move in a direction from and to an engagement surface for the valve spindle means arranged in the chamber, for regulating the flow through the chamber in a direction from the one opening to the other.
In these known valves, the sealing means carried by the valve spindle has had the form of a flat plate provided with a valve washer which has coacted with a valve seat in the form of a flat annular engaging surface inside the through-flow chamber in the valve housing. This design of valve has however caused the valve plate washer to have a propensity for binding onto the valve seat. This constitutes a very troublesome disadvantage with these valves, which have usually been used as safety valves in the supply pipes for fresh water to hot water supply tanks, where this binding tendency can adv affect the safety of the installation in a serious manner.
In order to obviate this disadvantage it is also known to provide valves of the type described in the introduction with a so-called easing mechanism. This has taken the form of a lever, pivotally mounted in the valve housing and in engagement with the valve spindle. The spring loaded valve plate has been able to be opened from its normally closed position by the aid of this lever so that the valve plate has been eased from its seating. In spite of the users of such valves being recommended to carry out easing movements monthly, the problem of valve plates stuck to the seat, with the valve washers spoiled in consequence, has generally remained, since most of the users of such valves either forget or do not bother to carry out the recommended measure regularly.